A Statistical and Data Management Core (hereafter referred to as the Statistical Core) is proposed to (1) coordinate data collection, entry, and verification for ongoing studies and to update and maintain the associated data bases; (2) assist in the design and development of new clinical and laboratory based studies, creating and maintaining new data bases as required; and (3) to perform statistical analyses of data resulting from these studies. The present biostatisticians and data manager will continue in their respective roles, providing support that is essential to the success of the Program Project. They will continue to draw together data from diverse sources, make sure that these data are accurately entered into centralized Statistical Core data bases, and provide correct data and analyses to the project investigators are requested. To facilitate the accomplishment of (1) and (2), conversion of the Statistical Core computing environment to Windows 97, with ACCESS for data management is proposed. Important components of (2) include conducting power calculations to determine required sample sizes and appropriate study design, assisting in the development and updating of forms for data collection, and improving methods for obtaining data from laboratory computers. To accomplish (3), the Statistical Core will continue to use existing statistical tools, refining them for the particular applications of the Program Project and writing new computer programs to implement the refinements as needed. Meta-analysis, event history analysis, analysis of the dependence structure between different event processes occurring in the same patient, and new investigations of approaches for censored data are proposed to address difficult statistical problems that arise in the Program Project.